Helical springs are machine elements required in large quantities and different configurations in numerous fields of application. Helical springs, also referred to as wound torsion springs or coil springs, are normally produced with cylindrical, conical or barrel shapes from spring wire and are in the form of tension springs or compression springs depending on their load during use. Compression springs, in particular bearing springs, are required, for example, in large quantities for automobile construction. The spring characteristic can be influenced, inter alia, by sections of different pitch or with different pitch profiles and/or different spring diameters.
Nowadays, helical springs are normally produced by spring winding with the aid of numerically controlled spring winding machines. In this case, a wire (spring wire) is fed to a forming device of the spring winding machine, controlled by an NC control program, and is formed with the aid of tools of the forming device into a helical spring. The tools generally include one or more winding pins, whose position is adjustable, for defining and varying the diameter of spring turns, and one or more pitch tools which determine the local pitch of the spring turns in each phase of the manufacturing process.
Spring winding machines are on the one hand intended for producing many springs with a specific spring geometry within very tight tolerances, at a high production rate. On the other hand, an increasingly wide range of helical springs demands greater flexibility and short conversion times of the production facilities to ensure timely delivery with a high yield capability at the same time.
In respect of stringent quality requirements, for example, in the motor vehicle field, it is normal practice to check certain spring geometry data such as the diameter, length and/or pitch and/or pitch profile of the spring by suitable test equipment during manufacture and, in the event of discrepancies from the nominal geometry outside the tolerance limits, to vary manufacturing parameters such that the spring geometry remains within the tolerances. In spring winding machines with NC control manufacturing parameters can be varied by correcting the NC control program.
Hence, it could be helpful to provide methods which allow that a correction to an NC control program for a spring winding machine can be carried out quickly and objectively and, therefore, more efficiently than in the past when setting up a new manufacturing process or when improving a manufacturing process which has been set up. It could also be helpful to provide spring winding machines suitable for this purpose.